General Description

The MAX2720/MAX2721 evaluation kits (EV kits) simplify
evaluation of the MAX2720/MAX2721 direct I/Q modula-
tor with variable gain amplifier (VGA) and power amplifier
(PA) driver. The MAX2720 is optimized for RF frequen-
cies between 1700MHz and 2100MHz, while the
MAX2721 is optimized for RF frequencies between
2100MHz and 2500MHz. The EV kits are fully assembled
and tested, allowing simple evaluation of all device func-
tions. All signal ports utilize SMA connectors, providing a
convenient interface to RF test equipment.

Features

o Easy MAX2720/MAX2721 Evaluation
o All Critical Peripheral Components Included
o SMA Input and Output Signal Connectors
o RF Ports Matched to 1900MHz (MAX2720)
o RF Ports Matched to 2315MHz (MAX2721)
o Fully Assembled and Tested

Evaluate: MAX2720/MAX2721

MAX2720/MAX2721 Evaluation Kits

________________________________________________________________ Maxim Integrated Products

Components Common to MAX2720/MAX2721

19-1715; Rev 0; 4/00

For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.

Ordering Information

PART

TEMP. RANGE

IC PACKAGE

MAX2720EVKIT

-40

°C to +85°C

20 TSSOP-EP*

MAX2721EVKIT

-40

°C to +85°C

20 TSSOP-EP*

DESIGNATION

QTY

DESCRIPTION

C1, C4, C8,

C9, C14, C17

470pF

±10% ceramic caps (0402)

Murata GRM36X7R471K050A

2pF

±0.25pF ceramic cap (0402)

Murata GRM36COG020C050A

C3, C10, C13

1000pF

±10% ceramic caps (0402)

Murata GRM36X7R102K050A

C6, C7, C15,

C16, C22,

C23, C24

0.1

µF ±10% ceramic caps (0603)

Murata GRM39X7R104K016A

C11

3.0pF

±0.25pF ceramic cap (0402)

Murata GRM36COG030C050A

C18

47pF

±5% ceramic cap (0402)

Murata GRM36COG470J050A

C19

µF ±10% tantalum capacitor

AVX TAJC106K010

C20, C21

Not installed

3.9nH

±5% inductor

Toko LL1608-FS3N9J

R1, R3

100k

resistors (0402)

10k

resistor (0402)

DESIGNATION

QTY

DESCRIPTION

20k

potentiometer

Bournes Digi-Key 3296W-203-ND

R5, R7,

R9, R11

1.00k

±1% resistors (0603)

R6, R8,

R10, R45

49.9

±1% resistors (0603)

J1, J3, J4, J5,

J7, J8

SMA edge-mount connectors
EFJohnson 142-0701-801

J2, J6

Not installed

J10, J11, J12

Test points

JU2

Not installed

JU4, JU5

1x3-pin headers (0.1in center)

JU6

1x2-pin header (0.1in center)

None

Shunts (JU4, JU5, JU6)

None

MAX2720/MAX2721 PC board

None

MAX2720/MAX2721 EV kit data
sheet

None

MAX2720/MAX2721 data sheet

*Exposed paddle

Evaluate: MAX2720/MAX2721

MAX2720/MAX2721 Evaluation Kits

_______________________________________________________________________________________

Quick Start

Test Equipment Required

· One low-noise RF-signal generator (50

source)

capable of delivering at least -10dBm of output power
over 1.7GHz to 2.5GHz (HP 8648C, for example)

· One I/Q generator capable of producing two 500kHz

sine waves, 90° out of phase with each other, with
an amplitude of 300mVp-p (HP 8904A with option 2,
for example)

· One dual-channel oscilloscope with a 100MHz mini-

mum bandwidth

· Two low-capacitance (<3.0pF) oscilloscope probes

(Tektronix P6201, for example)

· One spectrum analyzer capable of covering the

MAX2720/MAX2721 RF frequency range of the HP
8561E, for example

· Two 50

BNC-to-SMA cables

· Two 50

SMA cables

· One power supply capable of providing a minimum

of 150mA of supply current at +3V

· (Optional) Digital multimeters (DMMs) to monitor DC

supply voltage and supply current

· (Optional) A second power supply for varying the

gain of the modulator

I/Q Modulator Connections and Setup

1) DC Power Supply: Set the power-supply voltage to

+3V, and connect it to VCC and GND on the EV kit.
If desired, place an ammeter in series with the power
supply to measure supply current and a voltmeter in
parallel with VCC and GND to measure the supply
voltage delivered to the EV kit. Short jumper JU4 to
VCC to enable the device. Short jumper JU6 to allow
the potentiometer to vary the modulator gain; turn the
potentiometer until V

= 2.5V. If desired, open

jumper JU6 and connect to an additional voltage
supply to control the modulator gain.

2) LO Signal Source: The MAX2720/MAX2721 LO

port can be driven at full or half frequency. Connect
jumper JU5 (X2 ENB) to GND to enable the internal
LO frequency doubler, allowing the external LO sig-
nal source to operate at half frequency. Set the LO
signal source operating frequency to 950MHz
(MAX2720) or 1157.5MHz (MAX2721) at an output
power of -13dBm.

Connect jumper JU5 (X2 ENB) to VCC to disable the
internal LO frequency doubler, and run the external
LO source at the fundamental frequency. Set the LO
signal source frequency to 1900MHz (MAX2720) or
2315MHz (MAX2721) at an output power of -13dBm.
Connect the LO signal generator to the LO port SMA
connector using a 50

SMA cable.

3) I/Q Signal Source: Configure the dual-output func-

tion generator for a 500kHz IF frequency, with a
300mVp-p amplitude and a 90° phase difference
between channels. Connect a 50

cable from the

I/Q signal source to the EV kit's I+ and Q+ inputs.
The EV kit inputs are terminated with a 50

resistor

shunted to ground and a 1k

resistor in series with

DESIGNATION QTY

DESCRIPTION

8.0pF

±0.5pF ceramic cap (0402)

Murata GRM36COG080D050A

C12

resistor (0402)

1.5nH

±5% inductor

Toko LL1608-FS1N5J

1pF

±0.25pF ceramic cap (0402)

Murata GRM36COG010C050A

MAX2720EUP, 20-pin TSSOP-EP

DESIGNATION QTY

DESCRIPTION

6.0pF

±0.5pF ceramic cap (0402)

Murata GRM36COG060D050A

C12

27pF

±5% ceramic cap (0402)

Murata GRM36COG270J050A

1.2nH

±5% inductor

Toko LL 1608-FS1N2J

3.3nH

±5% inductor

Toko LL1608-FS3N3J

MAX2721EUP, 20-pin TSSOP-EP

MAX2720 EV Kit

Specific Components

MAX2721 EV Kit

Specific Components

SUPPLIER

PHONE

FAX

WEB

AVX

843-448-9411 843-448-1943

www.avxcorp.

com

EFJohnson

402-474-4800 402-474-4858

www.efjohnson.

com

Murata

800-831-9172 814-238-0490

www.murata.

com

Toko

800-pik-toko

708-699-1194

www.tokoam.

com

Component Suppliers

Evaluate: MAX2720/MAX2721

MAX2720/MAX2721 Evaluation Kits

_______________________________________________________________________________________

GND

DROUT

SHDN

GND

I -

I +

GND

Q +

Q -

GND

MODOUT

ENX2

470pF

VCC

3.9nH

2.0pF

SHDN

100k

1000pF

VCC

470pF

VCC

8pF

(5pF*)

0.1

VCC

470pF

C20

OPEN

R45

49.9

0.1

C18

47pF

C16

0.1

C15

0.1

VCC

C14

470pF

C13

1000pF

100k

C17

470pF

R10

49.9

VCC

49.9

10k

C12

(27pF*)

1pF

(3.3nH*)

1.5nH

(1.2nH*)

X2_ENB

VCC

470pF

C21

OPEN

R11

SMA

OPEN

C11

3.0pF

SMA

C19

C22

0.1

C23

0.1

C24

0.1

VCC

J11

JU6

JU2

20k

JU5

X2_ENB

VCC

J10

J12

SMA

JU4

SHDN

MAX2720

MAX2721

*COMPONENT VALUES ARE FOR MAX2721 ONLY.

DRIN

C10

1000pF

Figure 1. MAX2720/MAX2721 EV Kits Schematic

Evaluate: MAX2720/MAX2721

MAX2720/MAX2721 Evaluation Kits

_______________________________________________________________________________________

the baseband input of the MAX2720/MAX2721,
which has a 2k

(typ) input impedance. This volt-

age divider results in a 200mVp-p signal applied to
the MAX2720/MAX2721s' I+ and Q+ inputs. Use the
oscilloscope and its two probes to verify that the
amplitude difference between the two signals at the
I and Q inputs is at a minimum and the phase differ-
ence is 90°.

4) Spectrum Analyzer: Connect the spectrum analyz-

er to the MODOUT SMA connector using a 50

SMA cable. Set the spectrum analyzer's center fre-
quency to 1900MHz (MAX2720) or 2315MHz
(MAX2721). Set the spectrum analyzer's reference
level to 0dBm and the span to 1.2MHz.

I/Q Modulator Analysis

Turn on the power supply and the LO and I/Q signal
generators. The ammeter should read approximately
77mA (MAX2720) or 86mA (MAX2721) with the LO dou-
bler enabled, or 72mA (MAX2720) or 81mA (MAX2721)
with the LO doubler disabled.

Using the spectrum analyzer, observe the modulator
output spectrum. Notice three tones: the carrier, and
the lower and upper sidebands 500kHz below and
above the carrier. In its peak power setting (V

2.5V), the desired sideband will have an amplitude of
-8.5dBm (MAX2720) or -5.0dBm (MAX2721). The carri-
er suppression is typically 33dB (MAX2720) or 31dB
(MAX2721), while the sideband suppression is typically
40dB (MAX2720) or 35dB (MAX2721). Phase and
amplitude differences at the I and Q inputs result in
degradation of the carrier and sideband suppression.
Be sure to take into account board losses (0.3dB) when
calculating the output power of the device.

PA Driver Connections and Setup

1) DC Power Supply: Set the power-supply voltage to

+3V, and connect it to VCC and GND on the EV kit.
If desired, place an ammeter in series with the

power supply to measure supply current and a volt-
meter in parallel with the VCC and GND connec-
tions to measure the supply voltage delivered to the
EV kit. Short jumper JU4 to VCC to enable the
device.

2) Spectrum Analyzer: Connect the spectrum analyz-

er to the DROUT SMA connector using a 50

SMA

cable. Set the spectrum analyzer's center frequency
to 1900MHz (MAX2720) or 2315MHz (MAX2721).
Set the spectrum analyzer's reference level to
10dBm and the span to 1MHz.

3) RF Signal Source: Set the signal generator to an

output power of -12dBm at a frequency of 1900MHz
(MAX2720) or 2315MHz (MAX2721). Connect the
signal generator to the DRIN SMA connector using
a 50

SMA cable.

PA Driver Analysis

Turn on the power supply and RF signal generator. The
spectrum analyzer should measure an output power of
+1.5dBm (13.5dB gain) for the MAX2720 or -0.5dBm
(11.5dB gain) for the MAX2721. Be sure to take into
account board losses (0.3dB at the input, 0.3dB at the
output) when calculating the output power of the
device.

Layout and Bypassing

Good PC board layout is an essential aspect of RF cir-
cuit design. The MAX2720/MAX2721 EV board can
serve as a guide for layout of your board. Make sure
the input traces to the I and Q input pins are of equal
length and in the same environment as much as possi-
ble to keep the I and Q signals in quadrature for maxi-
mum sideband rejection at the modulated output. Keep
PC board trace lengths as short as possible to mini-
mize parasitics and losses. Keep bypass capacitors as
close to the device as possible with low-inductance
connections to the ground plane.

Part Number MAX2720EVKIT